Conductive and field emission properties of single and multi-walled carbon nanotubes

Just as silicon is the wonder material for the computer age, carbon nanotubes will most likely be the materials responsible for the next evolutionary step in electronics and computing. Their extraordinary properties have identified them as having the potential to revolutionise many technologies.

In particular, it is widely believed that carbon nanotubes will take electronic devices to the next level. Many people expect the hugely popular LCD and plasma screens of today to be replaced by field emission flat screen displays (FED-TV). FED-TV’s take all the best aspects of CRT’s, LCD’s and plasma TV’s and roll them into a single package. While the technology exists, manufacturers are at present unable to compete with LCD’s and plasma displays on a cost basis. However, carbon nanotubes have the ability to change all that.

In order to incorporate carbon nanotubes into devices like these field emission flat screen displays, an intimate knowledge of the properties of various forms of carbon nanotubes is invaluable. Researchers from University of Latvia, University College Cork, Trinity College Dublin, University of London and Mid Sweden University have just published work characterizing the conductive and field emission properties of single and multi walled carbon nanotubes.

The work by Jana Andzane, Joseph M. Tobin, Zhonglai Li, Juris Prikulis, Mark Baxendale, Håkan Olin, Justin D. Holmes and Donats Erts has been published in a special edition of the open access journal, AZoJono* and is available in its entirety at http://www.azonano.com/Details.asp?ArticleID=2038. This special edition of AZoJono features a number of papers from DESYGN-IT, the project seeking to secure Europe as the international scientific leader in the design, synthesis, growth, characterisation and application of nanotubes, nanowires and nanotube arrays for industrial technology.

In their work, the conductive and field emission properties of individual single and multi-walled carbon nanotubes were assessed using an in-situ transmission electron microscope-scanning tunnelling microscope (TEM-STM) technique. The nanotubes were grown by chemical vapour and supercritical fluid deposition techniques. Experimental field emission characteristics for all carbon nanotubes investigated fitted well to the Fowler-Nordheim equation when different work functions were applied. Differences in field emission and conductive properties are analysed and related to the structure of the carbon nanotubes. The method presented can be applied in order to make in situ selection of carbon nanotubes with desired properties for specific electronic applications.

The researchers found that conductivity and field emission properties were nanotube structure dependent. The structure of the outer layers and whether or not the nanotubes were filled with C60 molecules were key factors in determining the properties of the carbon nanotubes.

hese findings make a significant contribution to the understanding of the structure/property relationships for carbon nanotubes, which in turn bring the next generation flat panel televisions and monitors a bit closer to our lounge rooms and offices.

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